1. Field of the Invention
This invention relates to a method of and an apparatus for use in the production of coke, and more particularly to an improved method of an apparatus for handling coke oven doors, pushing coke from ovens, and charging the ovens with a uniform, level, compact charge of coal.
2. Description of the Prior Art
In the operation of banks of modern, nonregenerative coking ovens, the conventional practice is to charge the individual ovens, through charging holes in their tops, from cars which run along rails on the top of the bank of ovens. These cars carry hoppers which are normally filled with enough coal to completely charge an oven. Since the charging holes are spaced along the length of the ovens, the top surface of the charge of coal, as deposited, is uneven and must be leveled within the hot ovens to prevent uneven coking.
The coal charges are leveled in the coking chamber by an elonaged, substantially horizontal, cantilevered leveling bar which is telescoped into the coking chamber through a leveling bar opening in the oven door and moved back and forth over the top of the charge until the charge is more or less level. The bar is then withdrawn, the leveling bar opening is closed, and the coking process continues.
In view of the size of modern coking ovens, which may be in excess of 50 feet in length and up to 11 feet in width, it is readily seen that the cars employed to charge such ovens would necessarily be extremely heavy. The live weight of the cars, when loaded with a charge of 25 to 40 tons of coal or more, would put substantial stress on the bank of ovens.
The use of a leveling bar to level a charge of coke in an oven, particularly the modern, large, nonregenerative ovens, has not been entirely satisfactory for several reasons. In the first place, the leveling operation is time consuming and permits substantial heat loss from the oven as a result of the oven being open during the leveling operation. Further, the very large, wide ovens in use today are very difficult to level by passing a cantilivered bar projecting from its mobile support in front of the bank of ovens, back and forth over the surface of the charge in the oven. The tendency of such long leveling bars to droop toward the back of the oven tends to produce an uneven charge, and to compact the coal to a greater extent toward the back of the oven. Also, withdrawing the pusher bar from the hot oven invariably drags a quantity of coal out of the oven through the pusher opening. This coal may be ignited from the intense heat of the oven, a fact which further complicates the task of cleaning up or removing the coal.
Once the coking process is completed, a pushing machine which moves along tracks in front of the bank of ovens (and which normally supports the leveling bar) is positioned in front of the particular oven, and the front (pusher) and rear (coke) doors of the oven are removed. A large ram having a pusher head substantially the width of the coking chamber is forced through the pusher door opening and into contact with the cake of hot coke in the oven. Sufficient force is applied to the ram to force the cake of coke through the coking chamber and out the coke door into a hot car or other suitable receptacle positioned adjacent the coke door. Immediately upon receiving the charge of incandescent coke, the hot car is transferred to a quenching shed where the coke is quenched with water.
The intense heat of the coke, and of the oven walls, is extremely damaging to the pusher head. Even though these heads are normally constructed of heavy, heat-resistant alloy steels, the extreme temperatures and heavy loads to which they are subjected results in their quickly becoming warped and distorted, frequently to the extent that they do not do a good job of pushing the coke from the oven. In normal use, a pusher head of conventional construction may have a life expectancy of 6 weeks or less.
Numerous attempts have been made in the past to overcome the difficulties in charging and pushing coke ovens by the conventional process. For example, numerous devices have been proposed for side-loading the ovens, i.e., loading the ovens through the pusher door, or through the leveler bar opening in the pusher door. For example, U.S. Pat. No. 2,754,981 discloses a centrifugal blower structure for blowing coal into an oven through the normal leveler bar opening in the pusher door. While such a device may be useful in charging the coking chamber of a narrow regenerative retort (which may have a total width on the order of 18 inches), it can not be employed to deposit a uniform, level charge of coal in a large, nonrecovery oven which may have a width of from 6 to 11 feet, or more, and a length of from 30 to more than 50 feet. Further, even if the discharge end of a centrifugal blower conduit could be controlled accurately enough to deposit a level charge in such a large oven, the time required to charge the oven would be prohibitively long, and the intense heat of the oven, which may be as high as 2,000 to 2,600.degree. F during the charging operation, would soon destroy the conveyor structure. Also, such a device would be totally ineffective in compacting the top surface of the charge of coal.
Other side-loading devices, including screw-type conveyers, centrifugal throwers, and endless chain conveyers, have also been proposed to avoid the defects of the conventional top-loading process; however, these devices generally have been unsuccessful, with the result that the prevelant current practice is still to charge the ovens through the top as described above.